<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Simple Calculator</title>
</head>
<body>
<h1>Simple Calculator</h1>
<form action="/calculate" method="post">
    <input type="number" name="num1" required> +
    <input type="number" name="num2" required>
    <select name="operation">
        <option value="add">Add</option>
        <option value="subtract">Subtract</option>
        <option value="multiply">Multiply</option>
        <option value="divide">Divide</option>
    </select>
    <button type="submit">Calculate</button>
</form>
</body>
</html>
